Elastic, heat and moisture resistant bicomponent and biconstituent fibers

Abstract

Fibers having improved resistance to moisture at elevated temperatures comprise at least two elastic polymers, one polymer heat-settable and the other polymer heat-resistant, the heat-resistant polymer comprising at least a portion of the exterior surface of the fiber. The fibers typically have a bicomponent and/or a biconstituent core/sheath morphology. Typically, the core comprises an elastic thermoplastic urethane, and the sheath comprises a homogeneously branched polyolefin, preferably a homogeneously branched substantially linear ethylene polymer.

1. A fiber having an exterior surface, the fiber comprising at least two elastic polymers, one polymer heat-settable such that when formed into a fiber and (a) elongated 100 percent under tension, (b) exposed to a heat-setting temperature, and (c) cooled to room temperature, will resist shrinkage up to a temperature of 110° C., and the other polymer is crosslinked polyethylene crosslinked to have a gel-content of more than 30 wt % to provide heat-resistance, the crosslinked polyethylene comprising at least a portion of the exterior surface and wherein the fiber will recover at least 50 percent of the stretched length after both the first pull and the fourth pull to 100 percent strain. 
     
     
       2. The fiber of  claim 1  further comprising a compatibilizer. 
     
     
       3. The fiber of  claim 2  in which the compatibilizer is a functionalized ethylene polymer. 
     
     
       4. The fiber of  claim 3  in which the compatibilizer is an ethylene polymer containing at least one anhydride or acid group. 
     
     
       5. The fiber of  claim 4  in which the compatibilizer has been reacted with an amine. 
     
     
       6. The fiber of  claim 1  in which the polyethylene is a homogenously branched, substantially linear ethylene polymer. 
     
     
       7. A woven or knitted fabric comprising the fiber of  claim 1 . 
     
     
       8. A nonwoven fabric comprising the fiber of  claim 1 . 
     
     
       9. A woven or knitted fabric comprising between 1 and 30 weight percent based on the weight of the fabric of the fiber of  claim 1 . 
     
     
       10. A woven or knitted fabric comprising between 1 and 30 weight percent based on the weight of the fabric of the fiber of  claim 1  in which the fabric exhibits reduced shrinkage, as compared to a fabric alike in all respects except for comprising said fiber, when exposed to moisture at an elevated temperature.